This project will investigate the ability of two or more potential metabolites of chloramphenicol to induce aplastic anemia in mice. The colony-forming cells (CFC) assay will be used to detect potential toxicity of these metabolites to the bone marrow. The carcinogenicity of the two compounds will also be investigated, as this action may relate to aplastic anemia. The hydroxylamine and hydroxamic acid metabolites will be synthesized by proven methods, then subjected to biological testing. A study of the in vivo metabolism of the compounds will also be performed. All chemical investigations will be conducted at the University of Miami, Rosenstiel School of Marine and Atmospheric Science; the biological investigations will be performed at the University of Kansas School of Medicine.